Engines may use a turbocharger to increase engine torque/power output density. In one example, a turbocharger may include a compressor and a turbine connected by a drive shaft, where the turbine is coupled to the exhaust manifold side and the compressor is coupled to the intake manifold side. In this way, the exhaust-driven turbine supplies energy to the compressor to increase the flow of air into the engine.
In one example configuration, the drive shaft arranged between a compressor wheel and a turbine wheel is rotatably mounted in corresponding rotor bearings on the turbine side and the compressor side. The rotor bearings can generally be sliding bearings or roller bearings with oil lubrication, for example engine oil. The engine oil may be conducted to the individual bearing points via a pressure line, for example. The lubricant can both lubricate and cool the bearings.
The inventors herein have recognized potential pitfalls with the above-described oil lubrication system. For example, heat flux near the turbocharger may affect the oil supply and/or oil drain of the turbocharger. An increased heat flux can result in overheating and associated carbonization or coking of the lubricating oil, clogging the supply and/or drain, and thus reducing turbocharger lubrication. As the turbocharger operates at high rotational speeds, reduced lubrication can result in bearing degradation, thus reducing engine performance. Further, coking may occur at various locations, including in the bearings, which can also degrade performance.
In one particular example where the turbocharger is mounted in the valley of a V-type engine with inboard exhaust conduits. The turbocharger bearing oil supply and oil drain may be within the valley and the oil drain may be narrow as it leads between the cylinder heads and exhaust conduits. The narrow passage may be particularly susceptible to oil coking. Build up of residues within this drain can restrict the line, further inhibiting lubrication of the turbocharger.
In one embodiment, the present disclosure provides a coolant jacket for a turbocharger oil drain that draws heat away from hot oil as it drains out of the turbocharger, reducing the temperature of the oil and mitigating oil coking.
In another example, the present disclosure presents a system including a turbocharger, comprising a turbocharger bearing housing supporting a turbocharger drive shaft; an oil drain including an inlet in fluidic communication with the turbocharger bearing housing and an outlet in fluidic communication with an oil sump; and a coolant jacket enveloping the oil drain. The coolant jacket is suitable to provide coolant to the turbocharger bearing housing and to draw heat from the hot oil within the oil drain as it exits the turbocharger. In this way, the oil drain cooling jacket can also perform the feeding of coolant to the turbocharger bearing housing, thereby eliminating at least one external coolant line to the turbocharger. Within the valley of a V-type engine space for tubing may be limited, because of this, the oil drain may be narrow and cooling the hot oil in the narrow oil drain reduces the possibility of oil coking which can result in residue build up and restriction of the drain.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.